The present invention relates generally to document separating and feeding machines, and more particularly to a machine uniquely adapted for separating and feeding bound booklets seriatim from a stacked supply thereof for movement of the booklets to subsequent apparatus for further processing.
Machines for feeding documents seriatim from a stack thereof have long been well known and have been used in a variety of paper handling applications with great commercial success. Generally, machines of this type typically include a suitable hopper for holding a stack of documents, usually in substantially vertical orientation, with each document lying in a substantially horizontal plane. A suitable feeding mechanism separates a document from the top or bottom of the stack, depending on whether the machine is designed to feed from the top or bottom of the stack, and feed it from the stack to a suitable take away feeding device which further feeds the document to another apparatus for further processing.
Machines of this type are ideally suited for use in connection with various types of document processing systems which may typically include printing and separating machines for printing customized documents on a web and separating the documents into individual sheets, collating machines which form collations of a basic document, such as the customized printed document, and one or more items of additional insert material, accumulating machines for properly arranging the customized printed document or documents with all of the insert material, inserting machines for inserting the collations into envelopes, and mailing machine which close and seal the flaps of the envelopes, print a postage indicia thereon, and stack the envelopes for deposit with the Postal Service. There are, of course, other types of document processing operations which can be performed on the documents and/or insert material, such as printing, folding, scoring, etc. Thus, the type of document feeding apparatus of the type to which the present invention relates has widely diverse application in the general field of document handling and processing.
One very important characteristic of the individual components and machines that make up such a document processing system is that they must be capable of operating very reliably at a high rate of speed in order to justify the relatively high cost of purchasing and maintaining these components and machines.
Extensive experience has shown that document separating and feeding machines of the type to which the present invention is related have achieved a high degree of design refinement and have proven to be highly successful in virtually all of the commercial applications for which they were intended. There are a number of different design concepts for these feeders, such as feeding from the top or bottom as mentioned above, and utilizing friction roller or reciprocating friction pusher feed elements, vacuum lift or vacuum pusher feed elements, grippers, clamp type devices, and all are used depending on the type of documents being handled and the manner in which the feeder best fits into the overall processing system.
One exception to the general degree of commercial success and acceptance of these document separating and feeding machines is in the field of handling bound booklets, and particularly bound booklets that are formed of relatively cheap, low grade paper that is thin, flexible, and/or flimsy, and in feeding such booklets through the discharge opening of a bottom feed type separating and feeding machine. Depending on certain preferences of the originators of the booklets and the nature of the booklets themselves, some are printed on relatively expensive, substantially high grade paper which has a substantial degree of rigidity and resistance to wrinkling or rumpling, as well as a relatively smooth surface texture with a low coefficient of friction. They also may be formatted to have relatively small dimensions. Such booklets can be fed almost as if they are single sheets of relatively stiff material, and few problems are encountered in feeding such booklets with most commercially available bottom type feeding machines. However, in many other situations, booklets are printed on the relatively inexpensive, low quality paper, which typically is very thin and flimsy, has relatively little rigidity and therefore wrinkles or rumples easily when handled, and may also have a relatively coarse surface texture with a high coefficient of friction, and therefore cannot be separated and fed by commercially available separating and feeding machines with the required degree of reliability for commercial success. Booklets printed on this type of paper typically crumple in response to the feeding forces imposed on the booklets by virtually all of the known bottom feed document separating and feeding machines, and tend to jam in the discharge openings of such machines.
More particularly, the main problem encountered in separating and feeding any type of bound booklet from the bottom of a stack thereof is that the feeding element exerts a normal force adjacent the location of the feeding element on the bottom cover or outer sheet of the booklet, and also exerts a forward directional force on the bottom cover or outer sheet. Typically, the normal force from the feeding element is localized in the area of the feeding element and is not of sufficient magnitude to be distributed throughout the booklet, especially at the leading or bound edge thereof. If the booklet is made from good quality paper, and possesses the rigidity and size characteristics mentioned above, the lack of normal force at the lead edge of the booklet by the feeding element will not present a problem because the paper has sufficient rigidity, especially in a small format, to retain its shape. Thus, when sufficient directional force is applied by the feeding element to the cover or outer sheet of the booklet to overcome the frictional resistance to movement of the opposite cover or outer sheet with the cover or outer sheet of the adjacent booklet, the entire booklet will move and will feed from the bottom of the stack without jamming in the discharge opening of the separating and feeding machine. The booklet will, in effect, move as if it were simply a single sheet of relatively thick and rigid material.
On the other hand, if the booklet is made of low quality paper having the characteristics mentioned above, and particularly if it is made to a large format such as standard 81/2 by 11 inches, and because the normal force from the feeding element is localized and not directed at the leading bound edge of the booklet, when the forward directional force from the feeding element moves the cover or outer sheet of the booklet, the remaining sheets and the opposite cover or outer sheet tend to remain in place in the stack due to the frictional resistance described above. This will cause the cover and any outer sheets that do commence movement to rumple and curve out of alignment, and the booklet will jam at the discharge opening of the separating and feeding machine. This can even occur in some types of top feeding machines which have discharge openings, but it is more likely to occur in a bottom type separating and feeding machine where the weight of the stack of booklets pressing on the bottom booklet would amplify the amount of normal force on substantially the entire area of the bottom booklet except at the leading edge. This further increases the tendency for the leading or bound edge of the booklet to remain in place while the lower portion of the booklet begins to move, thereby further increasing the likelihood that the lead edge of the booklet will rumple and curve upwardly and jam in the discharge opening.
Thus, it is apparent that there is a need for a document separating and feeding machine that is capable of separating and feeding bound booklets from the bottom of a stack thereof which are formed of relatively low quality, thin, flexible and flimsy paper at a substantial rate of speed and with a high degree of reliability.